☣️ UN 3468 • CLASS 2
Hydrogen in a metal hydride storage system contained in equipment
Placard: Flammable Gas. Training/quick-reference only — use current ERG + SOP/SOG for incident-specific actions.
🚒☣️
⚠️ This page is a quick-reference aid. For real incidents: stage upwind, isolate, deny entry, request Hazmat early, and consult the current ERG + SOP/SOG.
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Quick details
UN 3468
Class: 2
Placard type: Flammable Gas
ERG: Guide 115 (check current ERG)
Isolation: ERG 115: isolate 100m all directions initially; if tank/container involved in fire, isolate 800m all directions
Chemical & Response Details
| Also known as | Hydrogen gasDihydrogenMolecular hydrogenH2 |
| CAS Number | 1333-74-0 |
| Appearance | Colorless, odorless, tasteless gas at room temperature. Lighter than air. Stored in metal hydride matrix which releases hydrogen gas when heated or depressurized. |
| Flash Point | Not applicable (gas) |
| Boiling Point | -253C (-423F) |
| Vapor Density | 0.07 (lighter than air) |
| Water Reactivity | No significant reaction with water |
| Extinguishing | Dry chemical, CO2, water spray for cooling containers; foam not effective on gas fires |
| PPE | ⚠️ Level B minimum; SCBA required; antistatic protective clothing; avoid ignition sources; metal hydride storage adds mechanical hazard |
| Isolation | ERG 115: isolate 100m all directions initially; if tank/container involved in fire, isolate 800m all directions |
Chemical details are general reference only. Always verify with current SDS, ERG, and SOP/SOG.
Common hazards (high level)
- EXTREMELY FLAMMABLE.
- Will be easily ignited by heat, sparks or flames.
- Will form explosive mixtures with air.
- Vapors from liquefied gas are initially heavier than air and spread along ground.
- Vapors may travel to source of ignition and flash back.
- Cylinders exposed to fire may vent and release flammable gas through pressure relief devices.
- Containers may explode when heated.
- Ruptured cylinders may rocket.
First actions (field-minded)
- CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper
- Keep unauthorized personnel away.
- Stay upwind, uphill and/or upstream.
- Many gases are heavier than air and will spread along the ground and collect in low or confined areas
- Isolate spill or leak area for at least 100 meters (330 feet) in all directions.
- Consider initial downwind evacuation for at least 800 meters (1/2 mile).
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UN 3468 — Hydrogen in a metal hydride storage syst HAZMAT RADIO NOTE — UN 3468
Product: Hydrogen in a metal hydride storage system contained in equipment
Class 2 / Flammable Gas / ERG 115
PPE: Level B minimum; SCBA required; antistatic protective clothing; avoid ignition sources; metal hydride storage adds mechanical hazard
ISOLATION: ERG 115: isolate 100m all directions initially; if tank/container involved in fire, isolate 800m all directions
ACTION: Stage upwind · Isolate · Deny entry · Request HazmatRADIO
Use for: Quick radio or face-to-face size-up. Short, structured, field-ready.
=== IC HAZMAT BRIEFING ===
UN 3468 — Hydrogen in a metal hydride storage system contained in equipment
Class: 2 | Placard: Flammable Gas | ERG Guide: 115
Appearance: Colorless, odorless, tasteless gas at room temperature. Lighter than air. Stored in metal hydride matrix which releases hydrogen gas when heated or depressurized.
Water Reactivity: No significant reaction with water
Extinguishing: Dry chemical, CO2, water spray for cooling containers; foam not effective on gas fires
PPE: Level B minimum; SCBA required; antistatic protective clothing; avoid ignition sources; metal hydride storage adds mechanical hazard
Isolation: ERG 115: isolate 100m all directions initially; if tank/container involved in fire, isolate 800m all directions
— Key Hazards —
• EXTREMELY FLAMMABLE.
• Will be easily ignited by heat, sparks or flames.
• Will form explosive mixtures with air.
— First Actions —
• CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper
• Keep unauthorized personnel away.
• Stay upwind, uphill and/or upstream.
• Many gases are heavier than air and will spread along the ground and collect in low or confined areas
SOURCE: allfirefighter.com/hazmat/un/3468 | Always use current ERG + SOP/SOGIC BRIEFING
Use for: Incident command briefing, staging area whiteboard, or pre-entry team brief. Full chemical + response details.
UN3468 Hydrogen in a metal hydride storage system contained in equipment Cls2 ERG115 | allfirefighter.com/hazmat/un/3468SMS / 160 CHAR
Use for: Quick text to command or incoming units. Fits in a single SMS. Includes link to full page.
⚠️ Quick-reference only. Always use current ERG + SOP/SOG for incident-specific actions. Page: https://allfirefighter.com/hazmat/un/3468
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FAQ
EXTREMELY FLAMMABLE. Will be easily ignited by heat, sparks or flames. Will form explosive mixtures with air. Vapors from liquefied gas are initially heavier than air and spread along ground. Vapors may travel to source of ignition and flash back. Cylinders exposed to fire may vent and release flammable gas through pressure relief devices. Containers may explode when heated. Ruptured cylinders may rocket.
CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper Keep unauthorized personnel away. Stay upwind, uphill and/or upstream.
Level B minimum; SCBA required; antistatic protective clothing; avoid ignition sources; metal hydride storage adds mechanical hazard
No. This is a training/quick-reference aid only. Always consult the current ERG Guide 115 and your department SOP/SOG for incident-specific protective actions.
Sources (high level): DOT/PHMSA marking & class concepts + ERG usage principles. This page does not reproduce ERG guide text—always consult the current ERG for incident-specific protective actions.